This invention relates to improvements in apparatus for the planting of seedlings, particularly seedling trees, in any type of terrain, and particularly in rough terrain created as a result of rocks and boulders disposed at or just beneath the earth surface.
U.S. Pat. No. 3,931,774 issued Jan. 13, 1976 relates to a seedling planter apparatus which may be trailed behind a tractor or other towing vehicle and which may be operated by one man as during the course of a reforestation or other similar project. This apparatus includes a mobile frame adapted to travel over the ground with an arm being pivotally mounted to the frame and extending rearwardly from the mounting location. A dibble is carried by the free end of the arm which is adapted to cut into the ground when the arm is urged toward the ground by a hydraulic actuator during the forward travel of the frame. A seedling planter is carried by the arm rearwardly of the dibble and is constructed to support a seedling for planting in the cut made by the dibble. A dislodging mechanism is provided for dislodging seedlings from the planter into the cut. The apparatus is particularly notable in that it includes a detection device for detecting when the dibble has cut to a predetermined depth into the ground and for activating the seedling dislodging device when the predetermined depth has been reached. Means are also provided for swinging the arm toward and away from the ground. In the event that the dibble fails to achieve the predetermined depth due to an obstacle such as a rock or boulder, the seedling dislodging device fails to operate.
Planting apparatus designed and constructed by the assignee of the present invention following the general principles outlined in the above noted patent has been found to operate very effectively. The particular embodiment described in the above noted patent illustrates a planting means adapted to plant "bare root" tree seedlings. As is well known in the art, these seedlings are grown in a nursery to an age of approximately three years then lifted from the nursery and taken to the field where they are planted at the appropriate spacing exactly in the same bare root condition as they were pulled from the earth at the nursery.
The equipment described in the above noted patent is capable of planting the bare root tree seedlings in a fairly efficient manner. However, with the use of the equipment as illustrated in the above patent, problems can arise in that during the planting process the root of the seedling may be dragged in the cut made by the dibble thus curling the root around into the shape of a "J". This problem is fairly common in mechanized planting operations and the term "J-root" has become a well known term in this art. "J-root" tends to impair the normal developments of the tree seedling and its elimination is considered to be most desirable.
A newer technology which assists in overcoming the J-root problem involves growing each seedling at the nursery in a small container, which container may be in the form of a hollowed out pocket or cavity in a block of styrofoam or alternatively the tree may be grown in a cylindrical tube of special paper. When the seedlings are planted in the field, their roots are surrounded by a plug of the nursery earth and sometimes even the paper container which eventually disintegrates. The container seedlings require special attachments to the planter to allow mechanized planting.